The couple's gift will be spread over the next five years and is the biggest allocation to date of the USD 1.1 billion in Facebook stock the couple pledged last year to the nonprofit Silicon Valley Community Foundation.

"Education is incredibly expensive and this is a drop in the bucket. What we are trying to do is catalyse change by exploring and promoting the development of new interventions and new models," Chan said in an interview at Facebook's Menlo Park, California, headquarters.

The first USD 5 million will go to school districts in San Francisco, Ravenswood and Redwood City and will focus on principal training, classroom technology and helping students transition from the 8th to the 9th grade. The couple and their foundation, called Startup: Education, determined the issues of most urgent need based on discussions with school administrators and local leaders.

It was Chan's first significant step into the public spotlight and the couple's premier interview together. The two met while studying at Harvard and married in their Palo Alto backyard on May 19, 2012 the day after Facebook's stock began publicly trading in a rocky initial public offering that now seems a distant memory. In 2010, they joined Giving Pledge, an effort led by Microsoft founder Bill Gates and Berkshire Hathaway CEO Warren Buffett to get the country's richest people to donate most of their wealth.

"I'm really focused on connecting the world. That's my main thing, and you're primarily focused on children," said Zuckerberg, turning to Chan. "And we're able to do some of this work together, which is neat...There are interesting overlaps."

Chan, 29, and Zuckerberg, 30, have made philanthropy a central theme of their life together. The two made the largest charitable gift on record for 2013. That USD 1.1 billion donation was on top of another USD 500 million the couple gave a year earlier to the Silicon Valley foundation, which helps donors allocate their gifts.